Rock-drill spool valve



June 15 1926. 1,589,255

W. A. SMITH ROCK DRILL SPOOL VALVE Filed April 15. 1925 2 Sheets-Sheet l INVENTOR. IE1; iamZIm 57/72 2175 AfTRNEYS.

June 15, 1926. 1,589,255

w. A. SMITH ROCK DRILL SPOOL VALVE Filed April 15. 1925 2 Sheets-Sheet 2 I N VEN TOR.

Patented June 15, 1926.

' lll ll l l lli WILLIAM A. SMITH, OE ATHENS, PENNSYLVANIA, ASSIGNOR TO INGERSOLL-BAND CGIVIPANY, OF JERSEY CITY, NE'VV JERSEY, A CCRPORATIOIT OF NEEV JEBSEY.

ROCK-DRILL SPOOL VALVE.

Application filed April 15, 1925. Serial No. 23,181.

This invention relates to fluid actuated rock drills of the hammer type, but more particularly to an improved spool valve for controlling both the inl t and exhaust of the cylinder.

The valve may he applied to various types of hammer drills, wit-h or without antomatic rotation 01 the drill steel, but is particularly advantageous with the automatical- 1y, rotated type of auger drill.

Theohject of the invention are to increase the speed of drilling in inches per minute maintain the speed of rotation. it automatic rotation is used, until the resistance to rotation causes sticking of the steel, prevent centering and fluttering of the valve and produce a rock drill which is easily held, it of the hand held type and is light and eco nomical in air consun'iption.

The invention is illustrated diagrammatically in one of its preferred forms in the accompanying drawings, in which Figure l is a longitudinal sectional elevation of so much of a rock drill as will serve tofmake the invention clear, and

Figures 2, 3 and l are similar views with the piston and valve in different positions.

T he diagrammatic drawings show the cylinder and reciprocating piston and the parts of the valve chest and valve in one of the simplest forms, without illustrating the automati rotation which may or may not he used as desired. but this feature iswell understood by those skilled in the art. The cylinder A is provided with the reciprocating hammer piston B having the head C and shank D which imparts blows of impact to the drill steel The distributing valve F travels rapidly hack and forth in the valve chest G which closed by the bushings ll held in position in any. suitable manner (not shown) and forming stops for the valve.

The bore of the valve chest G is shown of uniform diameter and the valve F is provided with the central head J and the end heads K and L, all of the same diameter. The end heads K and L are preferably hollow in order to lighten the valve construction and the inner or bottom "faces of the let. and the end heads K and L control the exhaust of the cylinder.

Supply passages R and S connect the valve chest with the ends of the cylinder A and valve controlling passages, usually descrioed as kicker ports T and U, connect the ends V and TV respectively of the valve chest G with cylinder ports X and Y located at each side of the center of the cylinder and controlled by the piston head C. As shown in this instance, these kicker ports T and U are crossed for the best operation oi the valve and supplemental leak ports a and 5 preferably connect the kicker ports T and U with the exhaust ports P and Q for the purpose o1 permitting leakage of pressure fluid from the ends of the valve chest to atmosphere.

The end heads K and L of the valve in this instance are formed with ports 0 and (Z which cooperate with the kicker ports T and U during rapid reciprocation of the valve in the valve chest and permit pressure fluid to he alternately trapped and released in the ends of the valve chest.

In the operation of the device let it be assumed that the piston is travelling forwardly as indicated in Figure l and the valve also in its "forward position, so that pressure fluid is being admitted from the in let 0 around the valve and through the supply passage S to the rearward end of the cylinder. As shown in Figure 1 the piston head C has arrived at a point in its travel which uncovers the cylinder port X of the passage T which permits pressure fluid under working pressure to pass through the port or ports 0 in the end head K of the valve to the end V of the valve chest. The pressure of this working fluid will start the valve in its rearward travel because the pressure in the opposite end N of the valve chest against the opposite end head L or the valve will have dropped suliiciently to be less than the working pressure. This drop in pressure in the opposite end W of the valve chest is due to the fact that the pressure fluid which was originally trapped in that end has expanded and there has also been a certain amount of leakage, although small, from said end around the valve and through the passage U and the leak port 6 to the exhaust port Q.

Referring to Figure 2 the piston B has continued its forward travel slightly and the valve has beenthrown to a position in which the opening of the passage T into the forward end of the valve chest has been closed by the valve head K so that working pressure fluid has been trapped in the forward end V of the valve-chest and at the same time the valve has been thrown far enough to open the rearward end lV of the valve chest to atmosphere through the: valve port (Z, passage S and leak port I). From the position of the valve indicated in Figure 2, t-he valve is moved for the remainder of its travel by the expansion of the pressure fluid trapped in the forward end of the valve chest, and Figure 3 shows the position of the valve as completely thrown rearwardly into position to admit pressure fluid from the inlet 0 around the valve and through the supply passage tothe -forward end of the cylinder to drive the piston rearwardly. The

piston is shown ashaving-completes its torward stroke and starting on its rearward stroke.

In Eigure 4:, the piston has reached a point in its rearward stroke in which the cylinder port Y otthe passage S is uncovered by the piston so that pressure fluid under working pressure is supplied to the rearward end W of the valve chest through the passage U and the valveport at to start the valve on its forward travel, since the pressure in the forward end V of the valve chest has dropped below working pressure, principally due to expansion of the fluid in throwing the valve, augn'iented by some leakage. From this point the cycle is repeated indefinitely.

I claim:

1. A fluid actuated rock drill of the hammer type, comprising a cylinder and reciprocating hammer piston, a valve chest having inlet and exhaust ports, a valve in said the cylinder and controlled by the piston for permitting pressure fluid under working pressure to pass alternately to the ends of the valve chest for starting the travel of the valve in one direction or the other, means for trapping the pressure fluid in one end of the valve chest and opening the other end to atmosphere, whereby the valve is thrown the balance of its travel due to the expansion of the trapped pressure fluid, and supplemental leak ports constantly. open to atmosphere connecting the valve controlling passages with the said exhaust ports in the va ve chest, for reducing the pressure of the trapped fluid after the valve has been actuat'ed.

2 A fluid actuated rock drill of thehaminer type, comprising a cylinder and reciprocating hammer piston, a valve chest having inlet and exhaust ports, a valve in said chest having a central head and end heads all of the same diameter, valve controlling passages connecting the ends of the valve chestwith ports at each side of the center 0t the cylinder and controlled by the piston, supplemental leak ports constantly open to atmosphere connecting the valve controlling passages with the said exhaust ports in the valve chest, and means for trapping pressure fluid in alternate ends of the valve chest.

In testimony whereof I have signed this specification.

WILLIAM A. SMITH. v 

